Lustful Male Marsupials Sacrifice Sleep for Intense Breeding Season
In the animal kingdom, mating rituals can often be fascinating and peculiar. One such example is the antechinus, an Australian marsupial that engages in a short but intense breeding season. These lustful male marsupials sacrifice their sleep for weeks to make more time for mating, resulting in a phenomenon that is both intriguing and tragic.
The antechinus, roughly the size of a gerbil, mates during a specific season and never again. Every August, male antechinus enter a three-week breeding frenzy, where they mate with as many females as possible before meeting their untimely demise. “It’s very short, very intense,” says zoologist Erika Zaid at La Trobe University in Melbourne, Australia. While males generally live for only one year, females can live longer and produce multiple litters.
To understand how these males manage to find enough time for mating in their short lives, Zaid and her colleagues conducted a study. They trapped ten male and five female dusky antechinus and kept them in separate enclosures to prevent mating. The researchers attached activity monitors to the animals’ collars and collected blood samples to measure biomarkers.
The findings revealed that captive males, but not females, exhibited increased movement and reduced sleep during the breeding season compared to the rest of the year. On average, the males’ sleep time per day was approximately 20% lower during the breeding season, with one male experiencing a sleep time reduction of over 50%. Shockingly, two of the males died within hours of each other at the end of the breeding season, while the remaining eight became sterile.
To determine if sleep loss occurs in the wild, Zaid and her team trapped 38 animals from a related species called agile antechinus before and during the breeding season. They measured the animals’ oxalic acid levels, a chemical in the blood that decreases when an animal experiences sleep deprivation. The results showed a sharp decline in males’ oxalic acid levels during the breeding season. Surprisingly, wild females also exhibited drops in oxalic acid levels, suggesting that males were waking them up for mating activities.
The study’s findings shed light on the mysterious deaths of male antechinus during the breeding season. While sleep loss was initially believed to be the cause, the two males that died were not the ones that had experienced the most sleep deprivation. Additionally, it takes much more sleep loss to kill a rat, indicating that something else is responsible for the demise of antechinus. “It’s a real question mark,” says Zaid.
Mammalian physiologist Adrian Bradley at the University of Queensland in Brisbane, Australia, commends the study as a thorough investigation. He shares his own experiences studying antechinus during the mating season, where males become hyperactive to the point of climbing his legs. Bradley suggests that changes in feeding patterns during the breeding season could lead to malnutrition and fatal damage to their stomachs.
In future studies, Zaid plans to delve deeper into what exactly kills these male antechinus. She suspects that an environmental trigger, such as a parasite, initiates a countdown before the mating season even begins. The quest to unravel this mystery continues, and perhaps one day we will fully understand the sacrifices made by these lustful male marsupials during their intense breeding season.
